<!DOCTYPE html>
<html lang="cn">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style type="text/css"></style>

</head>
<body>
    <h1>JS 的变量</h1>
    <hr>

    <script>
        var a = 'abcd 1234';
        var a = true;
        var a = false;
        var a = 666;
        var a = 666.66;
        var a = new Object();
        var a = new Array(1,561,616,156,156,6);
        var a = null;
        var a = undefined;
        var a = function () {
            alert('654321');
        }
        a();

        // alert(a);
        // document.write(a);


        
        console.log(a);
        console.log(typeof(a));

    </script>

</body>
</html>




